Put my game into Windowed Mode in an attempt to reduce graphical issues/crashing, and encountered a different problem: the text is distorted on certain lines. It's hard to describe, but it looks like the letters are squashed together across a horizontal line. It's worth saying that this does NOT happen in fullscreen, and changing resolutions didn't fix it. Any ideas?

Not about windowed mode, no, but you could try other things first to resolve crashing. We have a number of possible solutions here, and if the issue appears graphical in nature, make sure you have the latest graphics drivers. Don't use the device manager to check though, go to the graphicscard manufacturers' website.